Abstract

Sulfolobus strain LM was grown in tetrathionate and thiosulphate-limited continuous culture. CO2 limitation resulted in a decrease of the steady-state biomass and an increase in the specific rate of thiosulphate oxidation so that substrate did not accumulate in the medium. The initial step in thiosulphate utilization appeared to be its conversion to tetrathionate. The affinity for tetrathionate oxidation appeared to increase with prolonged continuous culture giving an apparent K(m) of about 6-mu-M tetrathionate, a higher affinity than for thiosulphate oxidation and in the same range as values observed with acidophilic, sulphur-oxidizing eubacteria.